An aquatic environment provides mosquitoes with a place to lay eggs, grow and develop through their eggs, larvae and pupal stages. Mosquitoes prefer stagnant water as a locus to lay their eggs. They commonly infest small bodies of water including ponds, stagnant creek areas, marshes, drain ditches, swamps and other wetland habitats. Many species of mosquitoes use containers of water as egg-deposit sites. Adults emerge from pupal cells, fly, rest then feed, mate, lay eggs, and may feed again (depending on group); oviposition is part of the airborne portion of their lifecycle. Water habitat is an excellent locus because that is where the larvae must reside, and certain insecticides kill the larvae and pupae, not the adults.
However, a problem encountered in delivering an insecticide to an aquatic environment is that the aquatic organism to be treated is not susceptible to contacting bioactive material. This is primarily because of the pest's location in a column of water either at the surface, the bottom, or some intermediate region in between may not contact the pesticide. Because of the difference in densities of the insecticide and the location of the pest, it cannot be targeted to precisely treat the pest organisms of interest in the water column. Depending of the location of the pest organism, it would be advantageous to target the column of water where the organism resides. If the pest organism is at the bottom, the surface or an intermediate layer in the water column, it would be advantageous to target that specific area of the pest's location.
Prior art products are too light and float on the surface of the water while drifting with wind (density less than 1). Further, light products may drift in the air and not apply as well to targeted locations, and may hang up in vegetation more easily because of their low specific gravity. Alternatively, products which are too heavy, sink (density greater than 1), and do not release the insecticide fast enough to be effective.
Bacillus thuringiensis israelensis (BTI) is an extensively used mosquito larvicide, which bacteria produces a toxic crystal glycoprotein (protoxin). BTI toxins have been used in the control a broad range of mosquito and blackfly species as well as nematodes mite and protozoa. Another potential microbial insecticide, Bacillus sphaericus, is known to be effective against Culex spp. and Anopheles spp. species, and has better residual activity in polluted waters by production of binary toxin (Bin) and mosquitocidal toxins (Mtx).
EP0349769 discloses Bacillus sphaericus bacteria genetically engineered with toxin producing genes taken from Bacillus thuringiensis israelensis (BTI) bacteria and transferred to Bacillus sphaericus strains. The genetically modified Bacillus sphaericus strains produced are capable of producing BTI toxins in effective amounts and can control against mosquito larvae and black flies effectively.
EP0454485 discloses using insecticide toxins obtained from Bacillus thuringiensis or Bacillus sphaericus bacteria against pests living in water such as mosquito larvae. The spores of these bacteria kill insect larvae feeding on these spores. The spores are digested in intestines of the larvae and release their toxins and neutralize the larvae.
Methoprene is an insect growth regulator and specifically a juvenile hormone analog which acts as a growth regulator when used as an insecticide. Methoprene mimics natural juvenile hormone and as juvenile hormone must be absent for a pupa to molt to an adult, methoprene-treated larvae are unable to successfully change from pupae to adults. U.S. Pat. No. 7,892,571 discloses a slow release carbon and S-methoprene composition as a solid flowable particulate for mosquito control. The slow release composition is contacted with water and slowly releases the S-methoprene directly into the aqueous locus.
In view of the foregoing, there is a need in the art to target aquatic pests that are resident in various locations within the water column. The present invention satisfies this and other needs.